The long term objective of this research is to improve the phenotypic characterization of autism by delineating the relative function of the interval timing system (ITS) in these individuals. The ITS is fundamental for adaptive cognitive and behavioral function, and there are theoretical, anecdotal and empirical grounds to suppose the ITS is dysfunctional in people with autism, and directly contributes to their triad of impairments. Only a handful of studies have assessed the ITS in autism, despite the fact that functioning of the ITS is being examined in other clinical populations (e.g., ADHD, schizophrenia). There are three specific aims of this research project that will fill gaps in our knowledge about autism, employing methodologies adapted from the basic laboratory (within the framework of scalar expectancy theory). The first aim (R00 phase) examines time perception (temporal bisection & generalization); the second aim (R00) examines timed performance (temporal reproduction & finger tapping); the third aim (K99 phase) employs fMRI to elucidate the neurological basis of preliminary data demonstrating quantifiable differences in time perception in autism (on temporal bisection; that correlates with scores on diagnostic tests). Results from K99/R00 studies will form the basis of an R01 application during the R00 cycle that will build upon the theoretical framework established during the K99 phase of the award and extend assessments of temporal information processing in autism. The support of a K99/R00 will provide the PI with mentored research training in developmental cognitive neurology, autism, fMRI (all at Johns Hopkins School of Medicine) and interval timing (with Dr. Warren Meck at Duke University), that extends and compliments her research background. Coupled with formal training classes, including autism diagnosis, this training plan will ensure the studies proposed during R00 can be successfully implemented. Research during the K99 phase will be conducted in the laboratory of Dr. Martha Denckla (primary mentor) who has a proven track record of supervising fellows into faculty positions. The proposed program of training and research will 'bridge' the transition to independence, and allow the PI to develop a unique and original line of autism research that will form the basis of her academic career.